JP2015200547A - Particle detection sensor, dust sensor, smoke detector, air cleaner and ventilator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a particle detection sensor capable of preventing particles from adhering inside.SOLUTION: A particle detection sensor 1 includes: a light projection element 10 and a light receiving element 20 for detecting particles contained in the atmosphere by receiving scattered light from a light projection element 10 due to particles in a detection area DA with a light receiving element 20. A first protection plate 61 which has the light transmissivity is disposed at a connection part between a particle flow path 33 which is a space area including a detection area DA where the atmosphere containing particles flows and a light-receiving area 32 as space area for guiding the scattered light to the light receiving element 20.

Description

  The present invention relates to a particle detection sensor, and a dust sensor, a smoke detector, an air cleaner and a ventilation fan provided with the particle detection sensor, and in particular, particles suspended in the atmosphere (aerosol) are detected by the scattered light of the particles. The present invention relates to a light scattering type particle detection sensor, an air cleaner using the same, and the like.

  The light scattering particle detection sensor is a photoelectric sensor including a light projecting element and a light receiving element, takes in a gas to be measured, irradiates the light of the light projecting element, and is contained in the gas by the scattered light. It detects the presence or absence of particles. For example, particles such as dust, pollen, and smoke floating in the atmosphere can be detected.

  As this type of light scattering type particle detection sensor, a sensor provided with a light trap at a position facing a light projecting element or a light receiving element is known in order to reduce the generation of stray light (see, for example, Patent Document 1). .

Japanese Patent Laid-Open No. 11-248629

  In the light scattering type particle detection sensor, particles are detected by introducing gas containing particles such as dust, pollen, smoke, etc. into the inside, so that the particles adhere to the inside of the particle detection sensor and the detection accuracy decreases. There is.

  This invention is made | formed in view of such a subject, and it aims at providing the particle | grain detection sensor etc. which can suppress that particle | grains adhere inside.

  In order to achieve the above object, an aspect of the particle detection sensor according to the present invention includes a housing, a light projecting element disposed in the housing, a particle disposed in the housing, and particles in the detection region. A light receiving element that receives the scattered light of the light from the light projecting element; a particle flow path that is provided in the housing and is a space area that includes the detection area and through which air containing particles flows; and A light receiving region which is provided in the housing and is a space region for guiding the scattered light to the light receiving element; and a connecting portion between the particle flow path and the light receiving region; And a first protective plate having the first protective plate.

  According to the present invention, it is possible to suppress the adhesion of particles inside the particle detection sensor, and thus it is possible to suppress a decrease in detection accuracy.

(A) is a top view of the particle detection sensor according to Embodiment 1 of the present invention, (b) is a front view of the particle detection sensor, (c) is a bottom view of the particle detection sensor, and (d). These are sectional drawings of the same particle detection sensor in an AA line of (a). It is sectional drawing for demonstrating operation | movement of the particle | grain detection sensor in case the particle | grains do not exist in air | atmosphere. It is sectional drawing for demonstrating operation | movement of the particle | grain detection sensor in case the particle | grains with a small particle diameter exist in air | atmosphere. It is sectional drawing for demonstrating operation | movement of the particle | grain detection sensor in case the particle | grains with a large particle diameter exist in air | atmosphere. It is a figure for demonstrating the positional relationship of the reflector in the particle | grain detection sensor which concerns on Embodiment 1 of this invention, a light receiving element, and a detection area. It is sectional drawing of the particle | grain detection sensor of a comparative example. It is a principal part expanded sectional view of the particle | grain detection sensor which shows a mode when the inside of the particle | grain detection sensor of the comparative example shown to FIG. 4A is cleaned. It is sectional drawing which shows the structure of the particle | grain detection sensor which concerns on Embodiment 2 of this invention. It is sectional drawing which shows the structure of the particle | grain detection sensor which concerns on Embodiment 3 of this invention. It is sectional drawing which shows the structure of the particle | grain detection sensor which concerns on Embodiment 4 of this invention. (A) is a top view of the particle detection sensor according to Embodiment 5 of the present invention, (b) is a front view of the particle detection sensor, (c) is a bottom view of the particle detection sensor, and (d). These are sectional drawings of the same particle detection sensor in an AA line of (a). It is a perspective view which shows a mode when the inside of the housing | casing of the particle | grain detection sensor which concerns on Embodiment 5 of this invention is cleaned (maintenance). It is sectional drawing which shows a mode when the inside of the housing | casing of the particle | grain detection sensor which concerns on Embodiment 5 of this invention is cleaned (maintenance).

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Each of the embodiments described below shows a preferred specific example of the present invention. Accordingly, numerical values, shapes, materials, components, arrangement positions and connection forms of components shown in the following embodiments are merely examples, and are not intended to limit the present invention. Therefore, among the constituent elements in the following embodiments, constituent elements that are not described in the independent claims showing the highest concept of the present invention are described as optional constituent elements.

  Each figure is a schematic diagram and is not necessarily illustrated strictly. Moreover, in each figure, the same code | symbol is attached | subjected to the substantially same structure, The overlapping description is abbreviate | omitted or simplified.

(Embodiment 1)
First, the configuration of the particle detection sensor according to Embodiment 1 of the present invention will be described with reference to FIG. 1A and 1B are diagrams showing a configuration of a particle detection sensor according to Embodiment 1 of the present invention. FIG. 1A is a top view, FIG. 1B is a front view, FIG. 1C is a bottom view, and FIG. It is sectional drawing in the AA of a).

  As shown in FIG. 1, the particle detection sensor 1 in the present embodiment is a photoelectric sensor including a light projecting element 10 and a light receiving element 20, and scattering of light from the light projecting element 10 by particles in the detection area DA. By detecting the light by the light receiving element 20, particles contained in the atmosphere are detected. The particle detection sensor 1 according to the present embodiment further includes a reflector 40 having a reflecting surface and a heating device 50 that heats the atmosphere, and a particle flow path 33 through which particles introduced into the interior pass. A first protective plate 61 having translucency is disposed at a connection portion between the light receiving region 32 which is a space region for guiding the scattered light of the particles to the light receiving element 20.

  The light projecting element 10 is a light source (light emitting unit) that emits light of a predetermined wavelength, and is, for example, a solid light emitting element such as an LED or a semiconductor laser. As the light projecting element 10, a light emitting element that emits infrared light, blue light, green light, red light, or ultraviolet light can be used.

  In addition, it becomes easy to detect a particle | grain with a small particle size, so that the light emission wavelength of the light projection element 10 is short. Moreover, the light emission control system of the light projecting element 10 is not particularly limited, and the light emitted from the light projecting element 10 can be continuous light or pulsed light by DC driving. Moreover, the magnitude | size of the output of the light projection element 10 may be changing temporally.

  The light receiving element 20 is a light receiving unit that receives light, and is an element (photodetector) that receives light and converts it into an electric signal, such as a photodiode, a photo IC diode, a phototransistor, or a high electron multiplier. .

  As shown in FIG. 1D, the light projecting element 10 and the light receiving element 20 are arranged in a housing 30 (case). The housing 30 is configured to hold the light projecting element 10 and the light receiving element 20. In the present embodiment, the light projecting element 10 and the light receiving element 20 are disposed in the housing 30 so that their optical axes intersect.

  In order to increase the light receiving sensitivity of the light receiving element 20, it is preferable to acquire a large amount of forward scattered light among the scattered light. In this case, the forward scattered light can be easily obtained by matching the optical axis of the light projecting element 10 and the optical axis of the light receiving element 20, but the optical axes of the light projecting element 10 and the light receiving element 20 are simply changed. If they are just matched, the light receiving element 20 will receive direct light from the light projecting element 10 in addition to the forward scattered light, and the particle detection accuracy will be reduced.

  For this reason, in this Embodiment, the optical axis of each of the light projection element 10 and the light receiving element 20 is made to cross | intersect. As an example, the angle formed by the optical axis of the light projecting element 10 and the optical axis of the light receiving element 20 is 60 degrees (120 degrees).

  In this way, by causing the optical axes of the light projecting element 10 and the light receiving element 20 to cross each other, the side scattered light in a portion close to the forward scattered light is not affected by the direct light from the light projecting element 10. Since it can acquire, the fall of the detection accuracy of particle | grains can be suppressed.

  As shown to (a)-(c) of FIG. 1, the external shape of the housing | casing 30 is a flat rectangular parallelepiped as an example. The housing 30 is composed of two members, a first housing portion 30a (lid portion) and a second housing portion 30b. A plurality of lead wires 11, 21, and 51 are exposed from the second housing portion 30b. The lead wires 11, 21, and 51 are electrically connected to the light projecting element 10, the light receiving element 20, and the heating device 50, respectively.

  In the housing 30, a light projecting region 31, which is a space region in which light from the light projecting element 10 is projected, and scattered light generated when the light from the light projecting device 10 hits particles in the detection region DA is guided to the light receiving device 20. For this purpose, a light receiving region 32 (diffuse light introducing portion), which is a space region, a particle flow path 33, which is a space region through which air (gas) containing particles flows, and a labyrinth portion 34 are provided.

  The light projecting area 31, the light receiving area 32, the particle flow path 33, and the labyrinth portion 34 are cylindrical space areas in the housing 30.

  For example, as shown in FIG. 1 (d), each of the light projecting region 31, the light receiving region 32, and the labyrinth portion 34 has a substantially cylindrical shape or a substantially rectangular tube shape that is surrounded by the inner surface (inner wall) of the housing 30. The bottomed cylindrical space region has an opening at a connection portion with the particle channel 33. That is, each of the light projecting region 31, the light receiving region 32, and the labyrinth portion 34 has an opening that opens toward the particle flow path 33, and is connected to the particle flow path 33 at each opening. In the present embodiment, each opening of the light projecting region 31, the light receiving region 32, and the labyrinth portion 34 opens toward the detection region DA.

  The particle flow path 33 is a gas passage region through which gas introduced into the housing 30 for measuring particles in the atmosphere is passed. The particle channel 33 is a cylindrical space region having a substantially cylindrical shape or a substantially rectangular tube shape and surrounded by the inner surface (inner wall) of the housing 30 and is a space region including the detection region DA. In the present embodiment, the particle channel 33 includes the entire detection area DA. In the present embodiment, the particle flow path 33 is a straight flow path from the air introduction hole 35 to the air discharge hole 36, and is connected to the light projecting area 31, the light receiving area 32, and the labyrinth portion in the middle of the flow path. Has been.

  Further, the inner surface (wall surface) of the housing 30 in the light projecting region 31, the light receiving region 32, the particle flow path 33, and the labyrinth portion 34 may be black in order to absorb light. For example, the housing 30 is a black resin molded product, and the exposed portion has at least a black surface inside.

  The detection area DA is an aerosol detection area (aerosol measurement unit) that is an area for detecting particles (aerosol) contained in the gas to be measured, and is a spatial area where the light projection area 31 and the light reception area 32 overlap. . The detection area DA is set so as to exist in the particle flow path 33. The gas to be measured is guided to the detection area DA through the particle channel 33.

  In the present embodiment, the flow channel direction of the particle flow channel 33 (the direction in which the gas to be measured flows) is the vertical direction on the paper surface of FIG. 1, but may be the vertical direction on the paper surface of FIG. That is, in the present embodiment, the flow channel axis of the particle flow channel 33 is set to exist on a plane through which each optical axis of the light projecting element 10 and the light receiving element 20 passes, but is orthogonal to the plane. It may be set as follows.

  The labyrinth unit 34 reflects that light that has passed through the detection area DA without hitting the particles in the detection area DA out of the light from the light projecting element 10 is reflected and scattered in the housing 30 and received by the light receiving element 20. It has a structure to prevent. Specifically, the labyrinth portion 34 has an optical trap structure, and has a light absorption structure that prevents light once entering the labyrinth portion 34 from exiting the labyrinth portion 34. For example, the inner surface of the housing 30 in the labyrinth portion 34 is provided with a plurality of black protrusions for multiple reflection and absorption of light.

  In the present embodiment, the labyrinth portion 34 (light trap structure) is provided at a position facing the light projecting element 10. Specifically, the opening of the labyrinth portion 34 faces the opening of the light projecting region 31. In the present embodiment, the labyrinth portion 34 is provided only at a position facing the light projecting element 10, but may be provided at a position facing both the light projecting element 10 and the light receiving element 20. However, it may be provided only at a position facing the light receiving element 20. However, in the case where the labyrinth portion 34 is provided only at a position facing the light receiving element 20, it is possible to provide means such as making the labyrinth portion 34 a through-hole so that the light once entering the labyrinth portion 34 does not return. Good.

  The housing 30 is provided with an air introduction hole 35 for introducing air into the particle flow path 33 and an air discharge hole 36 for releasing air from the particle flow path 33. The air introduction hole 35 is an air supply port for supplying the air existing outside the particle detection sensor 1 to the inside (particle flow path 33) of the particle detection sensor 1, and is connected to one of the particle flow paths 33. . On the other hand, the air discharge hole 36 is an air outlet for discharging the atmosphere inside the particle detection sensor 1 (particle flow path 33) to the outside of the particle detection sensor 1, and is connected to the other side of the particle flow path 33. .

  As a result, the atmosphere containing the particles (the gas to be measured) is introduced into the casing 30 from the atmosphere introduction hole 35 and flows into the detection area DA through the particle flow path 33, and from the atmosphere discharge hole 36 to the casing 30. Released outside. In the present embodiment, the air introduction hole 35 has a larger opening area than the air discharge hole 36 in order to efficiently introduce and exhaust the atmosphere into the housing 30.

  In the present embodiment, the light projecting area 31 is provided with a light projecting lens (light emitting lens) 31a. The light projecting lens 31a is disposed in front of the light projecting element 10, and is configured to advance light (projected beam) emitted from the light projecting element 10 toward the detection area DA. That is, the light emitted from the light projecting element 10 reaches the detection area DA via the light projecting lens 31a. The light projection lens 31a is, for example, a transparent resin lens or a glass lens.

  The light projecting lens 31a may be a collimating lens that collimates the light emitted from the light projecting element 10 toward the detection area DA, or the light that collects the light emitted from the light projecting element 10 on the detection area DA. Although a lens may be used, a lens that increases the light intensity of the light projecting element 10 in the detection area DA may be used as the light projecting lens 31a. Further, if the light intensity varies depending on the location in the detection area DA, the intensity of the scattered light varies depending on the location in the detection area DA even if the particles have the same particle size. A lens that makes the light intensity distribution of the element 10 uniform in the entire detection area DA may be used. Further, when the light from the light projecting element 10 is reflected on the wall surface of the housing 30, unnecessary reflected light and scattered light are generated. Therefore, as the light projecting lens 31a, the light from the light projecting element 10 is projected into the light projecting area 31. It is preferable to use a lens that directly reaches the detection area DA without being reflected by the wall surface of the housing 30 in FIG. The light projection lens 31a may not be provided.

  In the present embodiment, the light emitting area 31 is provided with a light emission stop portion 31b. The light emission stop 31b reduces the diameter of the condensed light by focusing unnecessary light on the light of the light projecting element 10 after passing through the light projecting lens 31a. The light emission diaphragm 31b is made of resin or the like, and is formed in a predetermined shape on the inner wall of the light projecting region 31. The light emission diaphragm portion 31b may be integrally formed with the housing 30.

  The reflector 40 (reflecting plate) is a reflecting member that reflects scattered light of the light projecting element 10 by particles in the detection area DA and guides the scattered light to the light receiving element 20. In the present embodiment, the reflector 40 reflects the scattered light of the particles and collects it on the light receiving element 20. More specifically, the reflector 40 reflects the scattered light of the particles toward the light receiving element 20.

  As shown in FIG. 1D, the reflector 40 is provided in the light receiving region 32 in the present embodiment. Specifically, the reflector 40 is a condensing mirror provided along the inner surface of the housing 30 in the light receiving region 32, and the inner surface which is a reflecting surface is a curved surface. As shown in FIG.1 (d), the inner surface of the reflector 40 is a part of rotation surface of a spheroid. That is, the reflector 40 is an elliptical mirror in which the shape of the inner surface (reflecting surface) forms a part of the spheroid, and the cross-sectional shape of the inner surface of the reflector 40 is a part of the ellipse.

  The reflector 40 has an opening that opens toward the particle channel 33. Specifically, the opening of the reflector 40 opens toward the detection area DA. In the present embodiment, the opening of the reflector 40 substantially coincides with the opening of the light receiving region 32. That is, the reflector 40 is provided up to the vicinity of the opening of the light receiving region 32. The end of the reflector 40 on the opening side is in contact with the first protective plate 61.

  As the reflector 40, the base member itself may be made of a reflective material such as metal so that the surface of the base member itself becomes a reflective surface, or a reflective film that becomes a reflective surface on the surface of a resin or metal base member May be formed.

As the reflection film, a metal reflection film such as aluminum, gold, silver or copper, a mirror reflection film, a dielectric multilayer film, or the like can be used. As the reflective film, a film having a low absorptance and a high reflectance is preferable. Moreover, you may use as a reflecting film what laminated | stacked the thin film thinner than the said aluminum film on the surface of the aluminum film formed by vapor deposition. As the thin film laminated on the aluminum film, for example, an MgF film, a SiO ₂ film, a SiO film, an AlN film, an alumina film, an enhanced reflection film, or the like is used. Thus, by laminating these thin films on the aluminum film, it is possible to suppress deterioration (corrosion and the like) of the aluminum film and improve optical characteristics by optical amplification.

  The heating device 50 heats the atmosphere in order to introduce the atmosphere containing particles into the detection area DA, and functions as an airflow generation device that generates an airflow for promoting the flow of the gas flowing in the particle flow path 33. To do. Specifically, the heating device 50 is a low-cost heater resistor or the like, and is disposed in the particle flow path 33 in the present embodiment. That is, the heating device 50 heats the atmosphere in the particle channel 33.

  For example, when the heating device 50 is a heater resistor, the heater resistor is heated when a voltage is applied to the heater resistor. As a result, the atmosphere around the heater resistor is heated to decrease the density, and moves upward in the direction opposite to gravity. That is, when the atmosphere in the particle flow path 33 is heated by the heating device 50, an upward airflow (upward airflow) can be generated.

  In this way, by heating the atmosphere in the particle flow path 33 by the heating device 50, the gas (atmosphere) to be measured can be easily drawn into the housing 30 (particle flow path 33). Compared with the case where 50 is not provided, more particles can be taken into the particle detection sensor 1. Therefore, since the amount of particles per unit volume in the detection area DA included in the particle flow path 33 can be increased, the sensitivity can be increased.

  Further, since the heating device 50 generates an ascending air current, it is preferable to install it in a lower portion of the particle flow path 33 as shown in FIG. Even when the heating device 50 is not operating, the atmosphere can pass through the particle flow path 33 between the atmosphere introduction hole 35 and the atmosphere discharge hole 36. That is, even when the heating device 50 is not operating, it is possible to detect particles contained in the atmosphere.

  The first protective plate 61 is a protective member that prevents particles such as dust, pollen, and smoke from entering the light receiving region 32, and is disposed in the housing 30. For example, the first protective plate 61 is used when particles floating in the atmosphere (dust, pollen, smoke, PM2.5, etc.) enter the housing 30 during operation and non-operation of the particle detection sensor 1. The particles are prevented from entering the light receiving region 32.

  As shown in FIG. 1 (d), in the present embodiment, the first protective plate 61 covers an opening (an opening of the light receiving region 32) serving as a connection portion between the light receiving region 32 and the particle flow path 33. Is arranged. That is, the first protective plate 61 is arranged so as to cover the light receiving region 32. By covering the opening of the light receiving area 32 with the first protective plate 61, the light receiving area 32 becomes a closed space area, and particles such as dust, pollen, and smoke are prevented from entering the light receiving area 32 from outside the light receiving area 32. it can.

  Further, in the present embodiment, the major axis of the ellipse (the optical axis of the reflector 40) and the light of the light receiving element 20 constituting the reflector 40 composed of the main surface of the first protective plate 61 and the rotation surface of the spheroid. The axis forms a right angle. In other words, the normal to the main surface of the first protective plate 61 is parallel to the major axis of the ellipse that constitutes the reflector 40 and the optical axis of the light receiving element 20.

  The 1st protection board 61 comprised in this way is a transparent board comprised by transparent resin, such as glass or a polycarbonate, an acryl, for example. The total transmittance of the first protective plate 61 is, for example, 99% or more if the Fresnel reflection is ignored. Further, as the first protective plate 61, a flat plate having a uniform thickness is used. That is, as the first protective plate 61, a flat plate having a constant plate thickness in the entire region is used. The first protective plate 61 may not be a flat plate having a uniform thickness. In order to attach the first protective plate 61 to the light receiving region 32, the first protective plate 61 has a thin peripheral portion. Or part of the peripheral edge may be cut out.

  The shape of the first protective plate 61 in plan view may be a shape that covers the opening of the light receiving region 32. For example, when the shape of the opening of the light receiving region 32 is circular, the first protective plate 61 is a circle. A plate-like transparent plate may be used.

  The first protective plate 61 is configured not to scatter scattered light of particles. That is, the surface of the first protective plate 61 is a smooth surface on both the main surface on the detection area DA side and the main surface on the light receiving element 20 side so that light is not scattered by the first protective plate 61.

  As the first protective plate 60, a flat plate having a refractive index of 1.5 or less and a thickness of 200 μm or less may be used. Thereby, the position shift of the optical path of the scattered light by the 1st protection board 60 can be made small.

  As will be described later, since the adhering matter adhering to the surface of the first protective plate 61 may be removed by rubbing with a cleaning tool such as a cotton swab, the surface of the first protective plate 61 has wear resistance. Good. Therefore, the surface of the first protective plate 61 is preferably subjected to surface treatment or surface coating treatment for improving wear resistance.

  Next, the operation of the particle detection sensor 1 according to the present embodiment will be described with reference to FIGS. 2A, 2B, and 2C. 2A to 2C show the operation of the particle detection sensor when there are no particles in the atmosphere, when particles with a small particle diameter exist in the atmosphere, and when particles with a large particle diameter exist in the atmosphere, respectively. It is sectional drawing for demonstrating.

  When the heating device 50 is operated to generate an air flow in the particle passage 33, the atmosphere is drawn into the particle detection sensor 1 from the atmosphere introduction hole 35, and the atmosphere passes through the particle passage 33 to the detection area DA. Led.

  In this case, as shown in FIG. 2A, when there is no particle (aerosol) in the atmosphere introduced into the particle detection sensor 1, that is, when the particle does not flow into the detection area DA, the light is emitted from the light projecting element 10. Since the light passes straight through the detection area DA, light scattered by particles is not generated. Therefore, in this case, basically, there is no reaction of the light receiving element 20, so that it can be seen that there are no particles in the atmosphere introduced into the particle detection sensor 1.

  In this case, light that has traveled straight after passing through the detection area DA may be reflected in the housing 30 and enter the light receiving element 20 as stray light. However, the light intensity detected by the light receiving element 20 is This is smaller than when particles are present in the detection area DA. Therefore, it can be seen that there are no particles in the atmosphere introduced into the particle detection sensor 1.

  In the present embodiment, since the labyrinth portion 34 is provided, the light that passes straight through the detection area DA is attenuated and absorbed by the labyrinth portion 34. As a result, it is possible to prevent light that has traveled straight through the detection area DA from entering the light receiving element 20 as stray light.

  In addition, as shown in FIG. 2B, when there is a particle (aerosol) P1 having a small particle size in the atmosphere introduced into the particle detection sensor 1, that is, when a particle P1 having a small particle size flows into the detection area DA. The light of the light projecting element 10 strikes the particle P1 existing in the detection area DA and is scattered, and the scattered light is reflected directly or by the reflector 40 and enters the light receiving element 20. When light enters the light receiving element 20, there is an output of a predetermined signal, so that it can be seen that particles exist in the atmosphere introduced into the particle detection sensor 1.

  In this case, since the light intensity of the scattered light detected by the light receiving element 20 is relatively small, it can be seen that particles having a small particle diameter exist in the atmosphere introduced into the particle detection sensor 1.

  In addition, as shown in FIG. 2C, when the particle (aerosol) P2 having a large particle size exists in the atmosphere introduced into the particle detection sensor 1, that is, when the particle P2 having a large particle size flows into the detection area DA. The light of the light projecting element 10 strikes the particles P2 existing in the detection area DA and is scattered, and the scattered light is reflected directly or by the reflector 40 and enters the light receiving element 20. When light enters the light receiving element 20, there is an output of a predetermined signal. In this case as well, it can be seen that particles are present in the atmosphere introduced into the particle detection sensor 1.

  In this case, since the light intensity of the scattered light detected by the light receiving element 20 is relatively high, it can be seen that particles P2 having a large particle size exist in the atmosphere introduced into the particle detection sensor 1.

  In this way, it is possible to detect whether or not particles are included in the atmosphere introduced into the particle detection sensor 1 by the scattered light from the particles (presence / absence of particles). That is, particles in the atmosphere can be detected.

  Further, the size (particle size) of the particle can be determined based on the size of the signal received by the light receiving element 20, that is, the light intensity of the scattered light from the particle.

  Further, each output of the signal detected by the light receiving element 20, that is, each peak of the light intensity of the scattered light by the particles corresponds to each of the particles. The number (amount) of particles in the atmosphere introduced into the interior can also be calculated.

  In particular, in the particle detection sensor 1 according to the present embodiment, the light receiving region 32 is provided with a reflector 40 for reflecting scattered light from particles in the detection region DA and guiding the scattered light to the light receiving element 20.

  Thereby, compared with the case where a lens is provided in the light receiving area 32, more scattered light generated by the particles in the detection area DA can be incident on the light receiving element 20. That is, the reflector 40 has a greater degree of design freedom than the lens, and thus can be shaped so that more scattered light can be guided to the light receiving element 20.

  For example, as shown in FIG. 1 (d), the opening of the reflector 40 can be extended to the limit of the opening of the light receiving region 32, and the prospective angle to the reflector 40 with respect to the detection region DA is increased. be able to. That is, since scattered light can be detected with a large solid angle, the light receiving sensitivity of the scattered light can be increased.

  Therefore, not only can the particles contained in the atmosphere be dust, pollen, or smoke, it is easy to detect fine particles with a small particle size such as PM2.5 (microparticulate matter). Can be determined.

  Further, in the present embodiment, the inner surface of the reflector 40 forms a part of the rotation surface of the spheroid. Here, the positional relationship among the reflector 40, the light receiving element 20, and the detection area DA and the function and effect thereof will be described in detail with reference to FIG. FIG. 3 is a diagram for explaining the positional relationship among the reflector, the light receiving element, and the detection region in the particle detection sensor according to Embodiment 1 of the present invention.

  As shown in FIG. 3, the reflector 40 in the present embodiment is an elliptical mirror, and one of the two focal points F1 and F2 in the ellipse constituting the spheroid is F1 (first focal point). ) In the detection area DA. The light receiving element 20 is disposed in the vicinity of the other focal point F2 (second focal point) of the ellipse.

  Thereby, the scattered light generated by the particles in the detection area DA can be incident on the light receiving element 20 with a small number of reflections (one or several times). That is, attenuation of light due to multiple reflection can be avoided. Therefore, since the light receiving efficiency in the light receiving element 20 can be increased, the sensitivity can be further increased.

  In the present embodiment, since the first protective plate 61 is disposed between the detection area DA and the light receiving element 20, the focus of the reflector 40 is taken into account in consideration of the refractive index of the first protective plate 61. The detection area DA and the light receiving element 20 may be disposed at the positions.

  Next, the operation and effect of the particle detection sensor 1 in the present embodiment will be described in comparison with the particle detection sensor 100 of the comparative example shown in FIGS. 4A and 4B. 4A is a cross-sectional view of the particle detection sensor of the comparative example, and FIG. 4B is an enlarged cross-sectional view of the main part of the particle detection sensor showing a state when the inside of the particle detection sensor of the comparative example shown in FIG. 4A is cleaned. It is.

  In the light scattering type particle detection sensor, particles are detected by introducing gas containing particles such as dust, pollen and smoke floating in the atmosphere, so the particles adhere to the inside of the particle detection sensor. As a result, the detection accuracy may decrease. In particular, when deposits accumulate inside due to long-term use, detection errors also increase. For example, it may be detected that the particles are present even though the particles should not exist, and an erroneous determination may be made.

  In view of this, as shown in FIG. 4A, a particle detection sensor 100 having a structure for removing deposits attached inside is considered.

  As illustrated in FIG. 4A, the particle detection sensor 100 of the comparative example includes a light projecting element 110 and a light receiving element 120, a housing 130 that holds the light projecting element 110 and the light receiving element 120, and a light projecting area 131. The lens 131 a disposed and the lens 132 a disposed in the light receiving region 132 are provided. And in the particle | grain detection sensor 100, the through-hole 170 for introducing a cleaning tool in the airflow passage area | region which is an area | region where the gas containing the particle | grains of detection object flows is provided in the housing | casing 130 so that the inside can be cleaned. Yes.

  In the particle detection sensor 100 of the comparative example, when cleaning the inside, as shown in FIG. 4B, a cleaning tool 200 such as a cotton swab is introduced from the through hole 170 to form the airflow passage region. Remove the deposits attached to the inner wall, etc.

  However, in the structure of the particle detection sensor 100 of the comparative example, since particles enter the light receiving region 132, the particles adhere to the lens 132a as adhering matter. Since the lens 132a collects the scattered light of the particles on the light receiving element 120, if the particles adhere to the lens 132a, the lens function of the lens 132a is affected, the light receiving sensitivity is lowered, and the detection accuracy is lowered.

  In addition, since the lens 132a is disposed in a deep part of the light receiving region 132, if particles adhere to the lens 132a, it is difficult to wipe off the deposit with a cleaning tool introduced from the through hole 170 as shown in FIG. 4B. . That is, although the deposits in the vicinity of the through-hole 170 can be easily wiped off, it is difficult to wipe off deposits that are present away from the through-hole 170. Further, as shown in FIG. 4A, the peripheral portion of the light receiving region 132 has an intricate structure and there are many corner portions. Therefore, a blind spot is formed by the corner portion, and the deposits present around the corner portion are wiped off. It has become difficult.

  As described above, in the particle detection sensor 100 of the comparative example, there is a problem that the detection accuracy is deteriorated by the particles attached in the light receiving region 132.

  By the way, in order to improve the light receiving sensitivity, it is considered that a reflecting plate (elliptical mirror or the like) having a rotating surface such as a spheroid instead of a lens is disposed in the light receiving region. As in the case of the particle detection sensor 100, it is difficult to clean the entire inner surface (reflecting surface) of the reflecting plate by a method of introducing a cleaning tool by providing a through hole in the housing.

  For this reason, in a particle detection sensor having a configuration in which a reflecting plate is arranged in the light receiving region, if an adhering material adheres to the inner surface of the reflecting plate, the amount of scattered light (the amount of received light) of the particles received by the light receiving element changes significantly. End up. As a result, the detection accuracy is greatly lowered and the reliability as the sensor is deteriorated.

  Therefore, in the particle detection sensor 1 according to the present embodiment, as shown in FIG. 1D, a first protective plate 61 having translucency is arranged at a connection portion between the particle flow path 33 and the light receiving region 32. ing.

  Thereby, since particles, such as dust, pollen, and smoke, can be prevented from entering the inside of the light receiving region 32, it is possible to suppress particles such as dust, pollen, smoke, etc. from adhering to the light receiving region 32. Therefore, it is possible to prevent the detection accuracy from being lowered due to the adhering matter adhering to the light receiving region 32.

  In the present embodiment, the first protective plate 61 is disposed so as to cover the opening of the light receiving region 32 (the opening serving as a connection portion with the particle channel 33).

  Thereby, the particles can be prevented from entering the inside of the light receiving region 32, so that the particles can be prevented from adhering in the light receiving region 32. Furthermore, once the light receiving area 32 is covered with the first protective plate 61, it is possible to prevent particles and the like from entering the light receiving area 32 even during the subsequent manufacturing process of the particle detection sensor 1. Can also be prevented.

  In the present embodiment, a reflector 40 that reflects scattered light of particles and guides the scattered light to the light receiving element 20 is provided between the first protective plate 61 and the light receiving element 20. For example, the inner surface of the reflector 40 is a part of the rotation surface of the spheroid and is an elliptical mirror.

  Thereby, it can suppress that the reflective surface of the reflector 40 becomes dirty by adhesion of particle | grains. That is, deposits such as particles are not accumulated on the reflection surface of the reflector 40. Therefore, since the reflectance of the reflecting surface of the reflector 40 does not change over a long period, the long-term reliability of the light receiving sensitivity and the detection accuracy can be improved.

  Further, by sealing the light receiving region 32 with the first protective plate 61, it is possible to prevent air and moisture from entering the light receiving region 32. Thereby, since it can prevent that the reflective surface of the reflector 40 corrodes, long-term reliability of a light reception sensitivity and a detection accuracy can be improved further.

  In the present embodiment, the main surface of the first protective plate 61 is perpendicular to the major axis of the ellipsoid of the spheroid constituting the inner surface of the reflector 40.

  Thereby, the scattered light of the particle | grains in the detection area DA can be efficiently transmitted through the first protective plate 61. Therefore, it is possible to prevent the light receiving sensitivity from being lowered by arranging the first protective plate 61.

  In the present embodiment, the width of the particle flow path 33 and the width of the detection area DA are preferably matched.

  Thereby, since all the gas containing the particle | grains introduce | transduced in the particle | grain detection sensor 1 will pass through the detection area | region DA, all the particles contained in the taken-in gas can be detected. Therefore, the detection probability of particles can be improved and the detection accuracy can be improved.

(Embodiment 2)
Next, a particle detection sensor 2 according to Embodiment 2 of the present invention will be described with reference to FIG. FIG. 5 is a cross-sectional view showing the configuration of the particle detection sensor according to Embodiment 2 of the present invention.

  As shown in FIG. 5, the particle detection sensor 2 in the present embodiment and the particle detection sensor 1 in the first embodiment are different in the arrangement of the first protective plate 61.

  Specifically, the first protective plate 61 in the first embodiment is arranged so that its main surface is perpendicular to the major axis of the ellipse that constitutes the reflector 40, whereas The first protective plate 61 in the embodiment is arranged so that the normal line of the main surface thereof is inclined with respect to the major axis of the ellipse constituting the reflector 40.

  As described above, according to the particle detection sensor 2 in the present embodiment, the first protective plate 61 is disposed at the connection portion between the particle flow path 33 and the light receiving region 32 as in the first embodiment. Even during the operation of the sensor 2 and during the manufacturing process of the particle detection sensor 2, it is possible to suppress the adhesion of particles in the light receiving region 32. Therefore, a decrease in detection accuracy can be suppressed.

  Also in the present embodiment, since the first protective plate 61 is disposed so as to cover the opening of the light receiving region 32, it is possible to further suppress the adhesion of particles in the light receiving region 32.

  Also in this embodiment, since the reflection surface of the reflector 40 can be prevented from becoming dirty due to the adhesion of particles, the reflectance of the reflection surface of the reflector 40 does not change, and the long-term reliability of light receiving sensitivity and detection accuracy is improved. Can be improved.

  Furthermore, by sealing the light receiving region 32 with the first protective plate 61, it is possible to prevent air and moisture from entering the light receiving region 32. Thereby, since corrosion of the reflective surface of the reflector 40 can be prevented, the long-term reliability of the light receiving sensitivity and detection accuracy can be further improved.

  In the present embodiment, the normal line of the main surface of the first protective plate 61 is inclined with respect to the major axis of the ellipse that constitutes the spheroid of the reflector 40.

  Thereby, since the opening part of the reflector 40 can be extended to the limit of the opening part of the light-receiving region 32, a large number of reflection surfaces of the reflector 40 can be obtained, and thus the light-receiving sensitivity of the scattered light of the particles in the reflector 40 is easy. Can be high. Therefore, a particle detection sensor that can detect particles with high sensitivity can be realized.

(Embodiment 3)
Next, a particle detection sensor 3 according to Embodiment 3 of the present invention will be described with reference to FIG. FIG. 6 is a cross-sectional view showing the configuration of the particle detection sensor according to Embodiment 3 of the present invention.

  As shown in FIG. 6, the particle detection sensor 3 in the present embodiment and the particle detection sensor 1 in the first embodiment are different in the arrangement of the first protective plate 61.

  That is, the first protective plate 61 in the first embodiment is arranged only in the connection portion between the particle flow path 33 and the light receiving region 32, whereas the first protective plate 61 in the present embodiment is It is disposed not only at the connection portion between the particle flow path 33 and the light receiving region 32 but also at the connection portion between the particle flow path 33 and the labyrinth portion 34. Specifically, the first protective plate 61 in the present embodiment covers both the opening of the light receiving region 32 and the opening of the labyrinth portion 34.

  The first protective plate 61 constitutes a part of the particle channel 33. Specifically, the surface of the first protective plate 61 is a wall surface of the particle channel 33.

  As described above, according to the particle detection sensor 3 in the present embodiment, the first protective plate 61 is disposed at the connection portion between the particle flow path 33 and the light receiving region 32 and at the connection portion between the particle flow path 33 and the light receiving region 32. Yes.

  Thereby, it is possible to prevent particles floating in the atmosphere from entering not only the light receiving region 32 but also the labyrinth portion 34. Therefore, during the operation of the particle detection sensor 3 and during the manufacturing process of the particle detection sensor 2. Moreover, it can suppress that particle | grains adhere in the light-receiving area | region 32 and the labyrinth part 34. FIG. Therefore, a decrease in detection accuracy can be suppressed.

  Also in this embodiment, since the reflection surface of the reflector 40 can be prevented from becoming dirty due to the adhesion of particles, the reflectance of the reflection surface of the reflector 40 does not change, and the long-term reliability of light receiving sensitivity and detection accuracy is improved. Can be improved. Moreover, since the reflectance of the labyrinth portion 34 is not changed by the reflector 40, the direct light from the light projecting element 10 that passes through the detection area DA when hitting the particles is reflected inside the housing 30 and received as stray light. It can also suppress entering into the element 20. FIG. Therefore, the long-term reliability of the light receiving sensitivity and detection accuracy can be further improved.

  In this case, by sealing the light receiving region 32 and the labyrinth portion 34 with the first protective plate 61, it is possible to block air and moisture from entering the light receiving region 32 and the labyrinth portion 34. Thereby, since corrosion of the reflective surface of the reflector 40 and deterioration of the labyrinth part 34 can be prevented, the long-term reliability of light receiving sensitivity and detection accuracy can be further improved.

  Further, in the present embodiment, the inside of the labyrinth portion 34 is not contaminated by the adhesion of particles, so that the reliability as a sensor is improved and the yield is improved.

(Embodiment 4)
Next, a particle detection sensor 4 according to Embodiment 4 of the present invention will be described with reference to FIG. FIG. 7 is a cross-sectional view showing the configuration of the particle detection sensor according to Embodiment 4 of the present invention.

  As shown in FIG. 7, the particle detection sensor 4 in the present embodiment has a configuration in which a second protective plate 62 is further arranged in the particle detection sensor 3 in the third embodiment.

  Specifically, the particle detection sensor 4 according to the present embodiment includes a first protection plate 61 disposed so as to cover the light receiving region 32 and the opening of the labyrinth portion 34, the light projecting region 31, and the particle flow path 33. And a second protective plate 62 disposed at the connection portion.

  In the present embodiment, the second protection plate 62 is disposed so as to face the first protection plate 61. That is, the second protective plate 62 and the first protective plate 61 are arranged in parallel.

  The second protective plate 62 is a protective member for preventing particles from entering the light projecting region 31. Specifically, the second protective plate 62 is disposed so as to cover an opening (an opening of the light projecting region 31) serving as a connection portion between the light projecting region 31 and the particle flow path 33. In other words, the second protective plate 62 is disposed so as to cover the light projecting region 31, and the light projecting region 31 is closed by covering the opening of the light projecting region 31 with the second protective plate 62. It becomes.

  The second protective plate 62 constitutes a part of the particle flow path 33 together with the first protective plate 61. Specifically, the surfaces of the first protection plate 61 and the second protection plate 62 are the wall surfaces of the particle passage 33, and the particles introduced into the particle passage 33 are the first protection plate 61 and the second protection plate. Passes between the plates 62.

  Similar to the first protection plate 61, the second protection plate 62 is a transparent plate made of, for example, glass or transparent resin, and the total transmittance is, for example, 99% or more if Fresnel reflection is ignored. Further, a flat plate having a uniform thickness is used as the second protective plate 62. Note that the second protective plate 62 may not be a flat plate having a uniform thickness. Like the first protective plate 61, the peripheral portion is thin or a part of the peripheral portion is notched. It may be.

  The shape of the second protective plate 62 in plan view may be a shape that covers the opening of the light projection region 31. For example, when the shape of the opening of the light projection region 31 is circular, the second protective plate 62 is A disc-shaped transparent plate may be used.

  The second protective plate 62 is also configured not to scatter the scattered light of the particles. That is, the surface of the second protective plate 62 is a smooth surface on both the main surface on the detection area DA side and the main surface on the light projecting element 10 side so that light is not scattered by the second protective plate 62.

  As will be described later, since the adhering matter adhering to the surface of the second protective plate 62 may be removed by rubbing with a cleaning tool such as a cotton swab, the surface of the second protective plate 62 has wear resistance. Good. Therefore, the surface of the second protective plate 62 is preferably subjected to surface treatment or surface coating treatment for improving wear resistance.

  As described above, according to the particle detection sensor 4 in the present embodiment, the first protective plate 61 is disposed at the connection portion between the particle flow path 33 and the light receiving region 32 and at the connection portion between the particle flow path 33 and the light receiving region 32. Therefore, the same effect as in the third embodiment can be obtained.

  Furthermore, in the present embodiment, the second protective plate 62 is disposed at the connection portion between the light projecting region 31 and the particle flow path 33.

  Thereby, it is possible to prevent particles floating in the atmosphere from entering the light projecting region 31 and to prevent particles from adhering to the light projecting region 31, and to use the light projecting lens 31a and the light emission diaphragm 31b. It is also possible to suppress adhesion of particles to the surface. Therefore, since the emitted light from the light projecting element 10 can be stabilized, the reliability as a sensor is improved.

  Moreover, since the light projection area | region 31 is covered with the 2nd protection board 62, the light projection lens 31a can be arrange | positioned in the back position of the light projection area | region 31, and the freedom degree of design of the light projection lens 31a increases. . That is, it is not necessary to dispose the light projecting lens 31a at a position close to the particle flow path 33 only to facilitate wiping off particles and the like attached to the light projecting lens 31a during maintenance.

  The space formed by the first protective plate 61 and the second protective plate 62 may form a part of the particle flow path 33 and coincide with the width of the detection area DA. For example, the space between the first protective plate 61 and the second protective plate 62 is configured to be a part of the particle flow path 33, and the distance between the first protective plate 61 and the second protective plate 62 is set. The width of the particle flow path 33 is preferably matched with the width of the detection area DA.

  As a result, all of the gas containing particles introduced into the particle detection sensor 4 passes through the particle flow path 33 that matches the width of the detection area DA, so that all particles contained in the taken-in gas are detected. can do. Therefore, the detection probability of particles can be improved and the detection accuracy can be improved.

(Embodiment 5)
Next, a particle detection sensor 5 according to Embodiment 5 of the present invention will be described with reference to FIG. FIG. 8 is a cross-sectional view showing the configuration of the particle detection sensor according to Embodiment 5 of the present invention, where (a) is a top view, (b) is a front view, (c) is a bottom view, and (d) is a bottom view. It is sectional drawing in the AA of (a).

  As shown in FIG. 8B, the particle detection sensor 5 in the present embodiment is the same as the particle detection sensor 4 in the fourth embodiment, and the housing 30 further includes a first protection plate 61 and a second protection plate. The cleaning tool introduction hole 37 into which the cleaning tool for removing the deposit | attachment adhering to the surface of 62 is introduced, and the lid | cover 38 which closes the cleaning tool introduction hole 37 are provided.

  Specifically, the cleaning tool introduction hole 37 is a through hole provided in the first housing portion 30a. The cleaning tool introduction hole 37 is configured such that the cleaning tool can be inserted from the horizontal direction of the main surface of the first protection plate 61 and the second protection plate 62. In the present embodiment, the cleaning tool introduction hole 37 is provided so as to open the horizontal direction of the main surfaces of the first protection plate 61 and the second protection plate 62, and more specifically, the first housing portion. 30a is provided so as to open a portion facing the first protection plate 61 and the second protection plate 62. That is, the cleaning tool introduction hole 37 opens a part of the particle flow path 33. Further, the cleaning tool introduction hole 37 is provided in a long shape along the direction in which the air flows in the particle flow path 33 (flow path direction).

  Except for cleaning the first protective plate 61 and the second protective plate 62 (when the particle detection sensor 5 is operating), the cleaning tool introduction hole 37 is closed by the lid 38. The lid 38 is detachably fitted in the cleaning tool introduction hole 37. Therefore, when cleaning the inside of the housing 30 such as the first protection plate 61 and the second protection plate 62, the lid 38 is removed to open the cleaning tool introduction hole 37, and a cleaning tool such as a cotton swab is removed from the cleaning tool introduction hole 37. Insert and clean the inside of the housing 30.

  As described above, according to the particle detection sensor 5 according to the present embodiment, by using the cleaning tool introduction hole 37, it is possible to perform maintenance for removing adhered substances such as particles attached in the housing 30. . For example, deposits attached to the surfaces of the first protective plate 61 and the second protective plate 62, the wall surface of the particle flow path 33, or other wall surfaces in the housing 30 can be removed.

  In this case, as shown in FIGS. 9A and 9B, a cleaning tool 200 such as a cotton swab is introduced from the cleaning tool introduction hole 37, and the surfaces of the first protection plate 61 and the second protection plate 62 (on the particle flow path 33 side). The adhering matter adhering to the surfaces of the first protective plate 61 and the second protective plate 62 can be wiped off by rubbing the surface) with the cleaning tool 200 or the like. 9A and 9B show a state when the inside of the housing of the particle detection sensor according to the present embodiment is cleaned (maintenance).

  Further, as shown in FIG. 8, in this embodiment, the cleaning tool introduction hole 37 is provided at a position facing the first protection plate 61 and the second protection plate 62. The adhered material adhered to the surfaces of the first protective plate 61 and the second protective plate 62 can be easily removed by the cleaning tool 200.

  Moreover, in this Embodiment, the cleaning tool introduction hole 37 is comprised so that the cleaning tool 200 can be inserted from the main surface horizontal direction of the 1st protection board 61 and the 2nd protection board 62. FIG. Thereby, when the cleaning tool 200 such as a cotton swab is inserted into the cleaning tool introduction hole 37, the cleaning tool 200 can be inserted from the horizontal direction of the main surfaces of the first protection plate 61 and the second protection plate 62.

  Then, as shown in FIGS. 9A and 9B, for example, the cleaning tool 200 is rubbed against the surfaces of the first protection plate 61 and the second protection plate 62 by the cleaning tool 200 inserted into the cleaning tool introduction hole 37. By moving the cleaning tool 200 back and forth along the direction perpendicular to the insertion direction of the cleaning tool 200, the deposits on the surfaces of the first protection plate 61 and the second protection plate 62 can be wiped off. Note that the moving direction of the cleaning tool 200 when scraping off the deposits on the first protection plate 61 and the second protection plate 62 is not limited to the direction perpendicular to the insertion direction of the cleaning tool 200, and the insertion of the cleaning tool 200 is not limited. It may be a direction or the like.

  Further, in the present embodiment, the cleaning tool introduction hole 37 is provided at a position where the main surface horizontal direction of the first protection plate 61 and the second protection plate 62 is opened. Thereby, the cleaning tool 200 can be easily inserted into the housing 30 from the horizontal direction of the main surfaces of the first protection plate 61 and the second protection plate 62 via the cleaning tool introduction hole 37.

  Further, in the present embodiment, the cleaning tool introduction hole 37 is provided in a long shape along the direction in which the air flows in the particle flow path 33. As a result, the cleaning tool 200 inserted into the cleaning tool introduction hole 37 is moved back and forth along the flow path direction of the particle flow path 33, thereby adhering substances on the main surfaces of the first protection plate 61 and the second protection plate 62. Can be easily wiped off.

  Further, in the present embodiment, the cleaning tool introduction hole 37 is closed by a lid 38 detachably attached to the cleaning tool introduction hole 37. Thereby, it is only necessary to remove the lid 38 only when cleaning the first protective plate 61 and the second protective plate 62, and the cleaning tool introduction hole 37 can be closed with the lid 38 except when cleaning. Therefore, cleaning (maintenance) can be performed without affecting the original sensor function of the particle detection sensor 5.

  This embodiment can also be applied to the first to third embodiments. In this case, the cleaning tool 200 is inserted into the cleaning tool introduction hole 37 in order to remove deposits attached to the surface of the first protection plate 61.

(Other variations)
As mentioned above, although the particle | grain detection sensor which concerns on this invention was demonstrated based on embodiment, this invention is not limited to said embodiment.

  For example, in the above embodiment, the cleaning tool introduction hole 37 is provided separately from the atmosphere introduction hole 35 and the atmosphere release hole 36 (that is, the cleaning tool introduction hole 37 was a hole dedicated for cleaning) The air introduction hole 35 and the air discharge hole 36 may be used as the cleaning tool introduction hole. In this case, a cleaning tool may be inserted from the air introduction hole 35 and the air discharge hole 36 to remove the deposits on the surfaces of the first protection plate 61 and the second protection plate 62.

  Further, in the above embodiment, the reflector 40 such as an elliptical mirror is disposed between the first protective plate 61 and the light receiving element 20, but the light is condensed between the first protective plate 61 and the light receiving element 20. A lens may be arranged. That is, a condensing lens may be disposed in the light receiving region 32 instead of the reflector 40. The condensing lens has a function of condensing the scattered light of the particles in the detection area DA onto the light receiving element 20.

  Moreover, in the said embodiment, although the inner surface of the reflector 40 was made into a part of rotating surface of a spheroid, it is not restricted to this, A part of rotating surface of the rotating body of conic curves, such as a rotation parabola It can also be. In this case, the conic curve may be selected from an ellipse, a parabola and a hyperbola instead of a circle. That is, the inner surface of the reflector is preferably a part of a spheroid, rotating parabola, or rotating hyperbolic curved surface (rotating surface) rather than a spherical curved surface (spherical surface). When the inner surface of the reflector is spherical, if diffuse reflection is used like an integrating sphere, scattered light is reflected (multiple reflection) and attenuated many times, so that light does not enter the light receiving element 20 so much. For example, in the case of a sphere, only about 1/100 is received compared to the case of a spheroid.

  Moreover, each particle | grain detection sensor in the said embodiment can be mounted in a dust sensor. For example, when the dust sensor detects dust particles with a built-in particle detection sensor, the dust sensor notifies the detection of dust by sound or light or displays it on a display unit.

  Moreover, each particle | grain detection sensor in the said embodiment can be mounted in a smoke sensor. For example, when the smoke detector detects smoke particles with a built-in particle detection sensor, the smoke detector notifies or displays on the display section that the smoke has been detected by sound or light.

  Moreover, each particle | grain detection sensor in the said embodiment or the said dust sensor can be mounted in an air cleaner or a ventilation fan. For example, when the dust purifier detects dust particles with the built-in particle detection sensor, the air cleaner or the ventilation fan may simply display that dust has been detected on the display unit, or activate the fan or rotate the fan. It is also possible to change the fan or to control the fan.

  In these devices, when the particle detection sensor 5 having the cleaning tool introduction hole 37 is used, the particle detection sensor 5 is built in the outer casing of the device. Even if a through hole is provided in a portion of the outer casing of the device facing the cleaning tool introduction hole 37 so that the first protective plate 61 and the second protective plate 62 can be easily cleaned by being inserted into the device 30. Good. Thereby, since the cleaning tool 200 can be inserted toward the cleaning tool introduction hole 37 from the said through-hole, the 1st protection board 61 and the 2nd protection board 62 can be cleaned easily.

  Moreover, in the said embodiment, although the medium containing particle | grains was air | atmosphere (air), media other than air | atmosphere (liquids, such as water), may be sufficient.

  In addition, the embodiment can be realized by arbitrarily combining the components and functions in each embodiment without departing from the scope of the present invention, or a form obtained by subjecting each embodiment to various modifications conceived by those skilled in the art. Forms are also included in the present invention.

DESCRIPTION OF SYMBOLS 1 Particle | grain detection sensor 10 Light emitting element 20, 120 Light receiving element 30 Case 31 Light emitting area 32 Light receiving area 33 Particle flow path 34 Labyrinth part 35 Atmospheric introduction hole 36 Atmospheric discharge hole 37 Cleaning tool introduction hole 38 Lid 40 Reflector 50 Heating Device 61 First protective plate 62 Second protective plate 200 Cleaning tool

Claims (29)

A housing,
A light projecting element disposed in the housing;
A light receiving element that is disposed in the housing and receives scattered light of the light projecting element by particles in a detection region;
A particle flow path which is provided in the housing and is a space region including the detection region and through which air containing particles flows; and
A light receiving region that is provided in the housing and is a spatial region for guiding the scattered light to the light receiving element;
A particle detection sensor, comprising: a first protective plate disposed at a connection portion between the particle flow path and the light receiving region and having translucency. The light receiving region has an opening at a connection portion with the particle channel,
The particle detection sensor according to claim 1, wherein the first protection plate is disposed so as to cover the opening of the light receiving region. The particle detection sensor according to claim 1, wherein a reflector that reflects the scattered light and guides the scattered light to the light receiving element is provided between the first protection plate and the light receiving element. The particle detection sensor according to claim 3, wherein an inner surface of the reflector is a part of a rotation surface of a spheroid. The particle detection sensor according to claim 4, wherein a main surface of the first protection plate is perpendicular to a major axis of an ellipse constituting the spheroid. The particle detection sensor according to claim 4, wherein a normal line of a main surface of the first protection plate is inclined with respect to a major axis of an ellipse constituting the spheroid. The reflector is arranged so that one focal point of the ellipse constituting the spheroid is present in the detection region,
The particle detection sensor according to claim 4, wherein the light receiving element is disposed in the vicinity of the other focal point of the ellipse. The particle detection sensor according to claim 2, wherein an end of the reflector on the opening side is in contact with the first protection plate. The particle detection sensor according to claim 1, wherein a condensing lens is provided between the first protection plate and the light receiving element. The particle detection sensor according to any one of claims 1 to 9, wherein the first protection plate is further disposed at a connection portion between the particle flow path and a labyrinth portion having an optical trap structure. The labyrinth portion has an opening at a connection portion with the particle flow path,
The particle detection sensor according to claim 10, wherein the first protection plate is disposed so as to cover the opening of the labyrinth portion. The particle detection sensor according to claim 1, wherein the first protection plate is a flat plate having a uniform thickness. The particle | grains of any one of Claims 1-12 in which the said housing | casing is provided with the cleaning tool introduction hole into which the cleaning tool for removing the deposit | attachment adhering to the said 1st protection board is introduce | transduced. Detection sensor. Furthermore, it has an air introduction hole for introducing the atmosphere into the particle flow path, and an air release hole for discharging the air from the particle flow path,
The particle detection sensor according to claim 13, wherein the cleaning tool introduction hole is provided separately from the atmosphere introduction hole and the atmosphere release hole. Furthermore, it has an air introduction hole for introducing the atmosphere into the particle flow path, and an air release hole for discharging the air from the particle flow path,
The particle detection sensor according to claim 13, wherein the cleaning tool introduction hole is at least one of the atmosphere introduction hole and the atmosphere discharge hole. Furthermore, it has a 2nd protection board arrange | positioned at the connection part of the light projection area | region which is the space area | region where the light of the said light projection element is projected, and the said particle flow path. The particle detection sensor described. The particle detection sensor according to claim 16, wherein a space formed by the first protection plate and the second protection plate forms a part of the particle flow path and coincides with the width of the detection region. The particle detection sensor according to claim 16, wherein the second protective plate is a flat plate having a uniform thickness. The particle detection sensor according to any one of claims 16 to 18, wherein the first protection plate and the second protection plate are arranged to be parallel to each other. The said housing | casing is provided with the cleaning tool introduction hole into which the cleaning tool for removing the deposit | attachment adhering to the said 1st protection board and the said 2nd protection board is introduce | transduced. 2. The particle detection sensor according to item 1. Furthermore, it has an air introduction hole for introducing the atmosphere into the particle flow path, and an air release hole for discharging the air from the particle flow path,
The particle detection sensor according to claim 20, wherein the cleaning tool introduction hole is provided separately from the atmosphere introduction hole and the atmosphere release hole. The particle detection sensor according to claim 14 or 21, wherein the cleaning tool introduction hole is configured such that the cleaning tool can be inserted from a horizontal direction of a main surface of the first protection plate. The particle detection sensor according to claim 22, wherein the cleaning tool introduction hole is provided so as to open a horizontal direction of a main surface of the first protection plate. The particle detection sensor according to claim 22 or 23, wherein the cleaning tool introduction hole is provided in a long shape along a direction in which air flows in the particle flow path. The particle detection sensor according to claim 14 or 21, wherein the cleaning tool introduction hole is blocked by a detachably attached lid. A dust sensor equipped with the particle detection sensor according to claim 1. A smoke detector equipped with the particle detection sensor according to any one of claims 1 to 25. An air cleaner equipped with the particle detection sensor according to any one of claims 1 to 25 or the dust sensor according to claim 26. A ventilation fan equipped with the particle detection sensor according to any one of claims 1 to 25 or the dust sensor according to claim 26.

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